Method and apparatus for integrating operation of a heat pump and a separate heating source

Abstract

A method and apparatus for integrating operation of a heat pump and a separate heating source are disclosed. The combination of a heating lockout relay and an interlock relay are utilized to provide for fail safe integrated operation including providing for selected control functions and for isolating other functions to prevent a failed electrical component from operating the system in an undesirable manner.

What is claimed is: 
     
       1. A control circuit for integrating and separating the operation of a heat pump including heating and defrost modes of operation and a separate heating means, the separate heating means including a circulator for circulating a heating fluid, the control circuit including a thermostat for sensing heating and cooling needs and an outdoor thermostat for selecting either the heat pump or the separate heating means for supplying heat energy to a space to be conditioned which comprises: a heating lockout relay connected to the control circuit to be energized when the thermostat senses a cooling need or when the unit is operated in the defrost mode of operation, said heating lockout relay preventing operation of the separate heating means when the heat pump is operating in the heating mode of operation;   a furnace boiler relay connected to be energized in response to the thermostat sensing a first stage heating need and the outdoor thermostat selecting furnace boiler operation and the heating lockout relay not being energized; and   a circulator relay connected to a fan energization switch of the thermostat for being energized either when the furnace boiler relay is not energized or when the heating lockout relay is energized such that the circulator relay is energized with the energization of the heat pump and not energized with the operation of the separate heating means.   
     
     
       2. The apparatus as set forth in claim 1 and further comprising an interlock relay connected through normally closed heating lockout relay contacts to the thermostat means such that the interlock relay may be energized upon the thermostat detecting a second stage heating need and the heating lockout relay not being energized. 
     
     
       3. The apparatus as set forth in claim 2 and further comprising: electrical connection means including normally open interlock relay contacts between the outdoor thermostat and the interlock relay such that the interlock relay will remain energized through now energized interlock relay contacts keeping the furnace boiler relay energized after the second stage heating need has been satisfied such that the separate heating means remains energized and the heat pump de-energized until both the first and second stage heating needs are satisfied.   
     
     
       4. The apparatus as set forth in claim 3 and further comprising: electrical circuit means connecting the outdoor thermostat to the compressor for energizing the compressor when the ambient temperature is above a predetermined temperature,   said electrical circuit means including a high temperature switch for sensing high refrigerant temperatures and normally closed interlock relay contacts such that the compressor may not be energized once a second stage heating need is satisfied until the interlock relay is de-energized, the interlock relay being energized until both the first and second heating stages are satisfied.   
     
     
       5. A method of integrating the operation of a heat pump including a compressor and having heating and defrost modes of operation and a separate heating means to provide for fail safe operation of the separate heat source, the separate heating means including a circulator for circulating a heating fluid to the enclosure to be conditioned, the control system for the separate heat sources including a thermostat for sensing heating and cooling needs and an outdoor thermostat for selecting either the heat pump or the separate heating means for supplying heat energy to a space to be conditioned which comprises the steps of: energizing a heating lockout relay when the thermostat senses a cooling need for the space to be conditioned;   energizing the heating lockout relay when the heat pump is operated in the defrost mode of operation;   the step of energizing the heating lockout relay including preventing a furnace boiler relay from being energized through the outdoor thermostat such that the separate heating means is not operated when a cooling need is sensed;   the step of energizing the heating lockout relay including connecting a-circulator relay for energizing the circulator of the separate heating means to a fan switch in the thermostat; and   the step of energizing the heating lockout relay including connecting defrost means to the furnace boiler relay for energizing the furnace boiler during the defrost mode of operation.   
     
     
       6. The method as set forth in claim 5 and further including an interlock relay for further separating control functions and further comprising the step of: preventing the interlock relay from being energized when the heating lockout relay is energized.   
     
     
       7. The method as set forth in claim 6 and further comprising the step of energizing the furnace boiler relay when the interlock relay is energized to supply heating to the space via the separate heating means. 
     
     
       8. The method as set forth in claim 6 and further comprising the steps of: energizing the interlock relay upon a second stage heating need being detected by the thermostat; and   maintaining the interlock relay energized after the second stage heating need has been satisfied but before the first stage heating need has been satisfied such that the separate heating means remains energized until both the first and second stage heating needs have been satisfied.   
     
     
       9. The method as set forth in claim 8 and further comprising the step of preventing the compressor of the heat pump from being energized when the interlock relay is energized thereby preventing heat pump operation during periods of separate heating means operation.